For the production of a carbon nanotube (NT) by a chemical vapor deposition (CVD) method, Si, SiO2, MgO, Al2O3 or the like has been hitherto used as a carrier of a catalytic metal such as Fe, Ni, Co, Pt, W and Mo. As a carbon source, an organic gas, such as methane, ethane, acetylene, benzene or an alcohol, or a CO gas is used. Such a carbon source is heated at a high temperature in the presence of the above catalyst to produce a single walled carbon nanotube (SWNT) by a CVD reaction.
With the above conventional method, however, it is necessary to remove the catalyst carrier after the formation of the carbon nanotubes because the carrier is an inorganic substance other than carbon (see, for example, Patent Documents 1 and 2). Thus, a burden is imposed by the recovery and refinement of carbon nanotubes, which poses a serial problem in practical application.
In conventional CVD methods, there is also a problem because it is difficult to control the length of carbon nanotubes.
Patent Document 1: Published Japanese Translation of PCT International Application No. 2005-532976
Patent Document 1: Unexamined Japanese Patent Application Publication No. 2005-126323